Design

Like its predecessor in EMD's catalog, the SDP35, the SDP40 is essentially a high-horsepower freight locomotive with additional equipment for passenger train service.

In 1966, EMD updated their locomotive catalog with entirely new models, all powered by the new 645 diesel. These included six-axle models SD38, SD40 and SD45, in addition to the SDP40. All shared standardized components, including the frame, cab, generator, trucks, traction motors, and air brakes. The primary difference was the power output: SD38 = from a non-turbocharged V16, SD40 = from a turbocharged V16, and SD45 = from a turbocharged V20.

The SD40 and SDP40 were so similar that EMD published common operator's and service manuals to cover both.

Besides horsepower, the primary characteristic of a passenger locomotive at the time was the ability to provide steam to the passenger cars, for heating, cooking, and sometimes cooling. Secondary characteristics could include a higher gear ratio for faster running, addition of the graduated-release feature to the air brakes, type F tight-lock couplers to keep equipment together in the event of a derailment, or extra signals and communication equipment. Of these, the steam generator was the largest, and had the greatest impact on the locomotive's appearance. To...Read More